4,552 research outputs found
Quark-lepton symmetry and complementarity
We argue that the difference between the observed approximate quark-lepton
complementarity and the theoretical prediction based on realistic quark-lepton
symmetry within the seesaw mechanism may be adjusted by means of a triplet
contribution in the seesaw formula.Comment: 7 pages, RevTex
How multiplicity determines entropy and the derivation of the maximum entropy principle for complex systems
The maximum entropy principle (MEP) is a method for obtaining the most likely
distribution functions of observables from statistical systems, by maximizing
entropy under constraints. The MEP has found hundreds of applications in
ergodic and Markovian systems in statistical mechanics, information theory, and
statistics. For several decades there exists an ongoing controversy whether the
notion of the maximum entropy principle can be extended in a meaningful way to
non-extensive, non-ergodic, and complex statistical systems and processes. In
this paper we start by reviewing how Boltzmann-Gibbs-Shannon entropy is related
to multiplicities of independent random processes. We then show how the
relaxation of independence naturally leads to the most general entropies that
are compatible with the first three Shannon-Khinchin axioms, the
(c,d)-entropies. We demonstrate that the MEP is a perfectly consistent concept
for non-ergodic and complex statistical systems if their relative entropy can
be factored into a generalized multiplicity and a constraint term. The problem
of finding such a factorization reduces to finding an appropriate
representation of relative entropy in a linear basis. In a particular example
we show that path-dependent random processes with memory naturally require
specific generalized entropies. The example is the first exact derivation of a
generalized entropy from the microscopic properties of a path-dependent random
process.Comment: 6 pages, 1 figure. To appear in PNA
The Frobenius group T13 and the canonical see-saw mechanism applied to neutrino mixing
The compatibility of the Frobenius group T13 with the canonical see-saw
mechanism of neutrino mixing is examined. The Standard Model is extended in a
minimalist way, by introducing a family symmetry and three right-handed
neutrinos. To fit experiments and place constraints on the possibilities,
tribimaximal mixing is used as a guideline. The application of both a family
symmetry group and the canonical see-saw mechanism naturally generates small
neutrino masses. The various possibilities from combining these two models are
listed. Enough constraints are produced to narrow down the parameters of the
neutrino mass matrix to two. This is therefore a predictive model where
neutrino mass eigenvalues and allowed regions for neutrinoless double beta
decay are suggested.Comment: Accepted for publication in Physical Review D. 13 page
Effects of an extra U(1) axial condensate on the strong decays of pseudoscalar mesons
We consider a scenario (supported by some lattice results) in which a
U(1)-breaking condensate survives across the chiral transition in QCD. This
scenario has important consequences for the pseudoscalar-meson sector, which
can be studied using an effective Lagrangian model. In particular, generalizing
the results obtained in two previous papers, where the effects on the radiative
decays eta,eta' --> gamma gamma were studied, in this paper we study the
effects of the U(1) chiral condensate on the strong decays of the "light"
pseudoscalar mesons, i.e., eta,eta' --> 3pi^0; eta,eta' --> pi^+ pi^- pi^0;
eta' --> eta pi^0 pi^0; eta' --> eta pi^+ pi^-; and also on the strong decays
of an exotic ("heavy") SU(3)-singlet pseudoscalar state eta_X, predicted by the
model.Comment: One misprint in Eq. (2.10) has been eliminated; Eqs. (B.8) and (B.9)
in Appendix B have been corrected; 46 pages, 1 tabl
GeV Majorana Neutrinos in Top-quark Decay at the LHC
We explore the \Delta L=2 same-sign dilepton signal from top-quark decay via
a Majorana neutrino at the LHC in the top anti-top pair production samples. The
signature is same-sign dilepton plus multi-jets with no significant missing
energy. The most optimistic region lies where the Majorana neutrino mass is
between 15-65 GeV. For 300 fb^-1 integrated luminosity, it is possible to probe
S_{ij}, the effective mixing parameter, to order of 10^-5.Comment: 15 pages, 8 figure
Observing Signals of the Bulk Matter RS Model through Rare Decays of SUSY Particles
The bulk matter Randall-Sundrum (RS) model is a setup where Standard Model
(SM) matter and gauge fields reside in the bulk of 5D warped spacetime while
the Higgs field is confined on the IR brane. The wavefunctions of the 1st and
2nd generation matter particles are localized towards the UV brane and those of
the 3rd generation towards the IR brane, so that the hierarchical structure of
the Yukawa couplings arises geometrically without hierarchy in fundamental
parameters. This paper discusses an experimental test of this model in the case
where the Kaluza-Klein scale is far above the collider scale, but the model is
combined with 5D Minimal SUSY Standard Model (MSSM) and SUSY particles are in
the reach of collider experiments. A general SUSY breaking mass spectrum
consistent with the bulk matter RS model is considered: SUSY breaking sector
locates on the IR brane and its effects are mediated to 5D MSSM through a
hybrid of gravity mediation, gaugino mediation and gauge mediation. This paper
argues that it is possible to observe the signals of the bulk matter RS model
through rare decays of "almost SU(2) singlet mass eigenstates" that are induced
by flavor-violating gravity mediation contributions to matter soft SUSY
breaking terms
Running with Triplets: How Slepton Masses Change With Doubly-Charged Higgses
We examine the slepton masses of SUSYLR models and how they change due the
presence of light-doubly charged higgs bosons. We discover that the measurement
of the slepton masses could bound and even predict the value of the third
generation Yukawa coupling of leptons to the SU(2)_R Triplets. We also consider
the unification prospects for this model with the addition of left-handed, B -
L = 0 triplets--a model we call the Triplet Extended Supersymmetric Standard
Model (TESSM). Finally, we discuss the changes in the slepton masses due to the
presence of the SU(2)_L triplets.Comment: 20 pages, 6 figures, 4 table
A Model for Neutrino and Charged Lepton Masses in Extra Dimensions
We propose a model with one large submm size extra dimension in which the
gravity and right-handed (RH) neutrino propagate, but the three Standard Model
(SM) families are confined to fat branes of TeV^(-1) size or smaller. The
charged leptons and the light neutrinos receive mass from the five dimensional
Yukawa couplings with the SM singlet neutrino via electroweak Higgs, while the
KK excitations of the SM singlet neutrino gets large TeV scale masses from the
five dimensional Yukawa coupling with an electroweak singlet Higgs. The model
gives non-hierarchical light neutrino masses, accommodate hierarchical charged
lepton masses, and naturally explain why the light neutrino masses are so much
smaller compared to the charged lepton masses. Large neutrino mixing is
naturally expected in this scenario. The light neutrinos are Dirac particles in
this model, hence neutrinoless double beta decay is not allowed. The model has
also several interesting collider implications and can be tested at the LHC.Comment: 11 pages, no figure
Renormalization Group Evolution in the type I + II seesaw model
We carefully analyze the renormalization group equations in the type I + II
seesaw scenario in the extended standard model (SM) and minimal supersymmetric
standard model (MSSM). Furthermore, we present analytic formulae of the mixing
angles and phases and discuss the RG effect on the different mixing parameters
in the type II seesaw scenario. The renormalization group equations of the
angles have a contribution which is proportional to the mass squared difference
for a hierarchical spectrum. This is in contrast to the inverse proportionality
to the mass squared difference in the effective field theory case.Comment: 13 pages, 4 figures; corrected error due to wrong superfield
normalization in RG equations (24-28,C1-4) as well as error in RG equations
of mixing parameters (38,43); RG equations of mixing angles depend on
Majorana phase
Current algebra derivation of temperature dependence of hadron couplings with currents
The vector and the axial-vector meson couplings with the vector and the
axial-vector currents respectively at finite temperature have been obtained in
Ref. \cite{Mallik} by calculating all the relevant one-loop Feynman graphs with
vertices obtained from the effective chiral Lagrangian. On the other hand, the
same couplings were also derived in Ref.\cite{Ioffe1} by applying the method of
current algebra and the hypothesis of partial conservation of axial-vector
current (PCAC). The latter method appears to miss certain terms; in the case of
the vector meson coupling with the vector current, for example, a term
containing the coupling is missed. A similar situation would
also appear for the nucleon coupling with the nucleon current. In this note we
resolve these differences.Comment: 7 pages, 2 eps figure
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